Accurately regulating the Ni coordination environment via atomic layer deposition and enabling efficient CO2 electroreduction

Abstract

Atomically dispersed transition metal-anchored nitrogen-doped carbon (M–N–C) catalysts demonstrate exceptional performance in the electrocatalytic CO₂ reduction reaction (CO₂RR), yet such default single-atom catalysts still encounter huge challenges due to the limited single-site catalytic capacity and high reaction energy barriers. Herein, we report an accurate regulation strategy for fabricating high-performance and robust xNi@NC-400H catalysts (x represents the cycles of deposition and H denotes H₂) by combining mild atomic layer deposition (ALD) and reduction post-treatment for the promising CO₂RR. Notably, the 5Ni@NC-400H catalyst with abundant dual-atomic Ni₂N₆ sites exhibits a CO faradaic efficiency (FE_CO) reaching 99.5% at −0.77 V vs. reversible hydrogen electrode (RHE) and maintains this at over 99% across a broad potential range from −0.37 to −1.17 V vs. RHE in a flow cell, and also exhibits excellent long-term stability. In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and density functional theory (DFT) calculations reveal that, in the 5Ni@NC-400H catalyst, the reaction intermediates adopt a bridge-adsorption configuration at the dual-atomic Ni₂N₆ site, which exhibits a higher electron-cloud density and a lower activation energy barrier than the single-atom NiN₄ site in the 1Ni@NC-400H catalyst, where the intermediates bind in a linear adsorption manner, thus significantly enhancing the CO₂ activation ability.